The present invention relates generally to cellular communication systems, and, in particular, to mobile stations and base stations that support multiple band classes in a cellular communication system.
The TIA/EIA (Telecommunications Industry Association/Electronic Industries Association) IS-2000 standard provides an Extended Channel Assignment Message (ECAM) that includes the capability for a communication system to assign a mobile station (MS) to a paging channel or a traffic channel in a different, alternate frequency band class than a frequency band class initially accessed by the MS. This capability, for example, allows the communication system to level the loads of multiple frequency band classes in the event that one of the band classes becomes particularly congested.
However, not all MS""s are able to support operations in each of multiple band classes. As a result, when an MS is accessing the communication system, and the communication system wishes to assign the MS to the alternate band class, the communication system must first determine the MS""s band class capability by engaging in a band class negotiation with the MS using Status Request/Status Response messages. The communication system sends a Status Request Message (SRM) on a forward common signaling channel (f-csch) that requests that the MS provide it""s band class capabilities. In response to receiving the SRM, the MS sends an Extended Status Response Message (ESRM) to the communication system on a reverse common signaling channel (r-csch) that informs of the MS""s band class capabilities. Upon receiving the ESRM, the communication system is then able to determine if the MS supports the alternate band class and send an ECAM to the MS. This exchange of messages on the common signaling channels prior to a channel assignment consumes system capacity, delays a call setup process, and can cause a higher probability of call setup failures.
Therefore a need exists for a method and an apparatus that determines an MS""s band class capabilities and assigns the MS to a new band class without the system capacity consumption and the call setup delay of the prior art.